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Cell Culture
Introduction Cell culture is the complex process by which cells are grown in artificial conditions, generally outside of their natural environment. The term "cell culture" has evolved to refer to the growing of cells havested from multi-cellular eukaryotes, especially animal cells. The term is not strictly limited to multicellular eukaryotes, however. There are of plant cultures, fungi cultures, insect cultures and microbial cultures, including viral, bacteria, and protist cultures (1). Cell culture development has historically been closely linked to the development of tissue culture and organ culture. History The English physiologist Sydney Ringer pioneered the concept of cell culture when he developed salt solutions containing specific chlorides (sodium, potassium, calcium, and magnesium) capable of maintaining the beating of an animal heart outside of the body. Further advances in the production of life-supporting solutions came from Ross Granville Harrison, who published results of experiments conducted at Johns Hopkins Medical School and later at Yale University from 1907 to 1910 that established the basis for cell culture methodology in the 20th century. Significant advances in cell culture were made in the 1940s and 50s to support research in virology. The development of viral cell culture allowed for the preparation of purified viruses that were in turn used to manufacture vaccines. The injectable polio vaccine developed by Jonas Salk was one of the first products mass-produced using cell culture. The polio vaccine came around as the result of cell culture research conducted by John Franklin Enders, Thomas Huckle Weller, and Frederick Chapman Robbins, who were awarded a Nobel Prize for their discovery of a method of growing the virus in monkey kidney cell cultures (2). Concepts Isolation of cells Cells can be isolated from tissue for ex vivo cultures in a number of ways. One approach is to digest cells in tissue using extracellular enzymes. Another technique is to place a single cell in growth media and allowing it to grow out for culture. This technique is termed explant culture. Cells derived directly from tissue culture are called primary cells. Most primary cell cultures have a limited lifespan, with the exception being primary cells derived from some tumors. However, through random mutation or deliberate modification, some cell cultures can be modified to multiply indefinitely. The culture resulting from such modifications is called an established or immortalized cell line. Maintaining cells in culture Cells are maintained at specific temperature, gas mixture, and humidity. Typically cell cultures will be incubated at close to physiological conditions. However, the modification of these factors can lead to different phenotypes. Growth medium is a major factor that is modified in cell culture systems. pH, the presence or absence of growth factors, and nutrient concentration are a few of the factors commonly altered in cell culture. Supplemental growth factors for media are frequently derived from the serum of animal blood. A third factor that plays a major role in the maintenance of cells in culture is plating density. Often cells will differentially express certain genes based on their surroundings, i.e., how many other cells are in their general area. Additionally cells can either be grown in suspension or in adherent cultures. This is relevant when growing cells that exist naturally in suspension, such as white blood cells that exist in circulation, as opposed to cells derived from solid tissue, which are usually adherent. Established human cell lines Cell lines derived from human origins have traditionally been controversial. Bioethics, the study of typically controversial ethics brought about by advance in biology and medicine, has focused on established human cell lines due to the fact that some cell lines may outlive their parent organism and later be used for the development of lucrative medical therapies. In 1990 the Supreme Court of California held in the landmark case Moore v. Regents of the University of California that human patients have no ownership rights to cell lines derived from their organs with their consent. Generation of hybridomas By fusing cells of interest with cancer cells, it is possible to create an immortalized cell line. This method is effective because it allows for the production of monoclonal antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cells. Monoclonal antibodies are hugely useful in the detection and purification of the substances they are designed to bind. References 1. Cell Culture. Wikipedia. http://en.wikipedia.org/wiki/Cell_culture 2. "Some landmarks in the development of tissue and cell culture". Retrieved 2014-09-25. http://www.ncbi.nlm.nih.gov/books/NBK26851/table/A1516/